Pipe slotter

ABSTRACT

A tube slotting assembly where tubing is placed in the annular space between an outer internally grooved cylindrical die and an inner cylindrical punch holder having slots in which radially movable punches are supported for outward movement against the internal tube surface, movement of the punches being controlled by a punch forcing cone which is longitudinally movable within the cylindrical punch holder.

United States Patent Salvador [45] Aug. 1, 1972 [54] PIPE SLOTTER 3,376,725 4/1968 Andrews ..72/311 72] Inventor: Mario 0 Salvador, Brantley Ave 1,432,073 10/1922 Lowy ..83/191 X Lake City SC 295 0 1,549,462 7 8/1925 De Wyk ..83/19l 1,764,129 61930 P b1 t 1 ..83 191 22 Filed: Oct. 7, 1970 rum e e a [21] Appl. No.: 78,841 Primary Examiner-Donald G. Kelly Att0rneyShlesinger, Arkwright & Garvey [52] US. Cl. ..83/l83, 29/163.5 R, 78247165855, [5 ABSTRACT 1 "1326f B231) 2 p 15/00 A tube slotting assembly where tubing is placed in the Fleld 0f Search 178, 202, annular space between an outer internally grooved 83/226, 684, 685; 72/311, 355; 29/ R cylindrical die and an inner cylindrical punch holder having slots in which radially movable punches are [56] References C'ted supported for outward movement against the internal UNITED STATES PATENTS tube surface, movement of the punches being controlled by a punch forcing cone which is longitudinally 1,625,131 4/1927 Miller ..72/355 movable within the cylindrical punch 1 1,693,011 11/1928 Woodward 29/1635 R 2,963,069 12/1960 Pasternak ..72/31 1 12 Claims, 11 Drawing Figures PATENTEDM 1 I97? I 3.680.422

sum 1 or 3 Fig. 2

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[N v ENTOR Mar/'0 0. Sa/vadar WW M ATTORNEYS PATENTEUAUG 1 I972 3.680.422

SHEET 2 OF 3 INVENTOR Mar/0 0 Salvador 5 4 y I 46 44 4046 m jjz wfy ATTORNEYS SUMMARY OF INVENTION This invention relates to machines for punching tubular stock materials, and more particularly for a tube slotting machine for producing well screens.

Presently, most well screens are produced by stamping out a plurality of slots on flat sheet stock and subsequently folding and butt or seam-welding the sides together to produce the slotted tubular screen. This method has a distinct drawback in that large stamping equipment is required, as well as complex seam-welding units. The screens when produced by this method can vary considerably from a circular cross-sectional configuration and have the additional drawback that in well screens produced by this method it is not possible to closely regulate the size of the slot openings.

Accordingly, it is an object of this invention to provide a machine for making well screens which will overcome these disadvantages.

It is'a further object of this invention to make is possible to manufacture well screens with less complicated and less costlyequipment.

The invention'contemplates the use of a radial punch and die assembly which will directly punch out the desired slots in tubing. The tubing is positively supported in an annular space between the internally grooved cylindrical outer die and the outer surface of a slotted cylindrical radial punch holder, through the slots of which the radial punches are moved in an outward direction to press out the contacted inner tubing surface. The inner ends of the radially movable punches are connected to a punch forcing cone which fits within the punch holder. The smaller end of the punch forcing cone is moved longitudinally into the bore of the punch holder so that its tapered surface presses the radial punches outwardly as its increasingly wider portions are pressed into the bore of the punch holder.

The invention also contemplates the provision of a special bench for slotting tubing in which the outer die and the punch holder are rigidly supported in a concentric spaced relation to each other to provide uniform annular spacing between them, and the tubing to be slotted is supported and progressively fed into the annular space. A powered ram moves the punch forcing cone into the bore of the punch holder at a desired incremental rate to provide accurate control of the radial displacement of the punches.

Other features and advantages of the invention will become apparent from an inspection of the following description and claims and drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a slotted well casing produced by the machine of the subject invention;

FIG. 2 is a side view of the radial punch and die assembly with the punch forcing cone and the cylindrical punch holder shown partially removed from their normally operable position within the cylindrical outer die;

FIG. 3 is an end view of the die assembly;

FIG. 4 is a cross-sectional view of the outer die assembly;

FIG. 5 is a cross-sectional view of the cylindrical punch holder;

FIG. 6 is a side view of the punch forcing cone;

FIG. 7 is a side view of one of the radial punches;

FIG. 8 is an end view of the punch of FIG. 7;

FIG. 9 is a cross-sectional view of the punch forcing cone illustrating the manner in which the radial punch is mounted thereon;

FIG. 10 is an enlarged view of a portion of the well screen of FIG. 1;

FIG. 11 is a top view of the pipe slotting machine of the subject invention.

DESCRIPTION OF THE INVENTION Referring particularly to the drawings, FIG. I shows a well screen unit 10 having a slotted central body 12. The slotted protrusions are arranged in circumferentially spaced rows, such as rows 14 and 15. A threaded end section 16 is provided at the top and the bottom of the screen, and an internally threaded collar 18 is shown threaded onto the top threaded section of the pipe screen.

The pipe screens can also be fabricated with no threading in either end and adapted for welding if desired.

The length of slotted pipe screen will depend upon the flow values and the open area made by the slots. The slotted screens are usually provided in lengths of 5 and 10 feet and are fabricated from well casings.

The tubular well casings have the plurality of slots punched out by the radial punch and die assembly 20 shown in FIGS. 2 and 3. It consists of an outer cylindrical die, a slotted cylindrical punch holder, and a punch forcing cone.

The cylindrical die 22, shown in FIGS. 2 to 4 has 18 longitudinally extending circumferentially spaced punch receiving die grooves 24 milled out of the internal surface 26 of the cylindrical die. Four alignment pin passages 28 extend through the die 22. Each end face has tapped support bolt receiving holes 29. The manner in which the assembly fits together is illustrated in FIGS. 2 and 3. The spacing and size of the longitudinal grooves 24 can be seen in FIGS. 3 and 4.

The slotted cylindrical punch holder shown in FIGS. 2, 3 and 5 has nine circumferentially spaced punch guiding slots 32 in which the radial punches are supported. Its cylindrical outer surface 34 has a diameter sufficiently smaller than the cylindrical die internal surface 26 to provide an annular clearance, as shown in FIG. 3, to accommodate the cylindrical well casing 12. Four radial alignment pin passageways 36 are aligned with the alignment pin passageways 28 of the outer cylindrical die 22. Tapped holes 37 are drilled in each end face to accommodate supporting bolts. The inner surface 38 of the cyclindrical radial punch holder has a diameter sufficiently large to receive the punch forcing cone 40 which forces the three radial punches 42 outwardly through their respective punch guiding slots 32. The cross-sectional view of the punch holder shown in FIG. 5 illustrates the configuration of the punch guiding slots 32.

The end view of the die assembly shown in FIG. 3 has a portion of the slotted punch holder 30 broken away to show the manner in which the punches are supported within the guide slot 32.

It can be seen that there is a necessity for a very accurate alignment between the several members of the die assembly, so that the radial punches 42 can move without binding or interference along the guide slots 32 and into the punch receiving grooves 24. The alignment problem can be appreciated considering that small clearances are used. The die receiving grooves are approximately three thousandths of an inch greater than the width of the punches 42.

To insure that that there is correct mounting and alignment between the outer die and the radial punch holder, an elongated alignment pin not shown, is passed through the alignment passages 28 of the outer die 22 and into the radially aligned alignment pin passages 36 of the cylindrical punch holder 30.

A side view of the punch cone 40 is shown in FIG. 6, and an enlarged sectional view is shown in FIG. 9. There are nine longitudinally extending holding grooves 44 which extend the entire length of the conical surface and are equally spaced circumferentially. Their cross-sectional configuration is that of an inverted T, and they are positioned for exact alignment with the nine punch guiding slots 32 of the cylindrical punch holder 30.

The longitudinal holding grooves 44 form intermediate longitudinal rib section 46 as illustrated in FIG. 9, which have projecting edges 49 extending outwardly over the holding grooves to engage the lower side surface of the radial punches 42, as illustrated in FIG. 9.

To provide for ease of movement of the lower portion of the radial punch as it traverses along the holding grooves 44 of the punch forcing cone, a grease fitting 48 shown in FIG. 6 is provided to supply grease to a plurality of radially extending grease supply passages 50 connected to each of the longitudinal holding grooves. A central grease passage 51 connects the radia] grease supply passages to the grease fitting 48.

The wide end of the punch forcing cone has a threaded connecting section 52 on which a locking nut 54 is disposed forconnection to a tubular shaft to be described hereafter which moves the punch forcing cone into and out of the bore of the cylindrical radial punch holder.

The radial punch elements used for a given slotting operation are all of the same shape. FIGS. 7 and 8 respectively show a side and an end view of the punch used in the die assembly. An upper front inclined section 56, an intermediate punch section 58, and an upper rear outwardly inclined section 60 are pressed outwardly radially and against the inner tubular wall of the well casing to be slotted, pressing out the section of the tubular casing to which it comes in contact.

The punch has rounded end faces 62 and a rounded bottom corner 64 on each edge. The slot 66 is cut on each face of the punch adjacent its lower edge and parallel thereto to provide a T-shaped lower section 68, which fits into the longitudinal slot 46 of the punch forcing cone 44.

The relative dimensions of the groove 46, and the punch retaining section 68 are dimensioned such that there is a free-sliding fit permitting the retaining section 68 to move freely along the longitudinal T-shaped slots of the punch forcing cone as it is moved inwardly or outwardly thereby radially moving the punches in their punch guiding slots 32. The punch members 42 are dimensioned so that they also will readily move in a close sliding fit in a radial direction along the radial slots 32 of the cylindrical radial punch holder.

FIG. 10 is a closeup of a section of slotted pipe screen 70 showing slotted pressed-out sections 72 and the opening 74 through which the fluid passes. Pressed section 76 is a direct top view of another slotted piece which is longitudinally and laterally offset from the punched out sections 72. All of the punched out sections are similar in shape, the shape being determined by the upper surface of the radial punches 42. The length of the central section 78 of the punched out piece conforms to that of the .radial punch used, and the intermediate surface, such as 58 of the punch of FIG. 7.

The above explains in detail the actual structural configuration and operation of the punch and die assembly 20 itself. In FIG. 11, the machine used to support and operate the punch and die assembly and to progressively feed the tubing to be slotted is illustrated.

FIG. 1 1 is a top view of the machine or slotting bench 80 which has two parallel side roller support rails 82 and 84 which extend the length of the unit.

An hydraulic cylinder 86 supplies the mechanical power to move the tubular pipe section through the die assembly to be slotted. Hydraulic fluid is supplied to the power cylinder through hydraulic supply lines 88. Shaft 89 is moved outwardly as desired, and is supported by the roller support assembly 90 which moves longitudinally with the shaft along the bench and is supported by rollers which engage the side support rails 82 and 84. A connecting collar assembly 92 is connected to the end of the shaft 89 at one side and to the length of well casing or tubing 94 to be slotted.

The punch and die assembly 20 shown in dotted outline, is supported by cross support plates 95 and 96 which are rigidly connected to the work bench and to the side rails 82 and 84.

Bolts are passed through the supporting plates into the corresponding bolt holes 28 of the outer cylindrical die. The bolt holes 37 of the cylindrical radial punch holder receive bolts that go into the end of the outer sleeve of the punch forcing cone shaft assembly 98. The alignment pins are used before the bolts are tightened.

It will be noted that the far end of the well casing 94 extends through the die assembly 20, passing through the annular clearance between the outer cylindrical die and the cylindrical radial punch holder, as shown in FIG. 3.

ln use the outer cylindrical die 22 and the cylindrical radial punch holder 30 are held rigidly in position, while the three radial punches 42 are moved outwardly against the tubing.

It will be noted that there are nine guide slots 32, and nine longitudinally extending holding grooves 44 on the conical punch forcing cone 40, and ordinarily, unless the tube wall is very thick, nine punches are used simultaneously. For purposes of illustration however, three punches are shown.

The first step in fabricating the slotted pipe is the mounting of the punch and die assembly 20 on the bench 80 of FIG. 11. The assembly is placed into position between the plates 95 and 96 and alignment pins are inserted through the alignment passages 28 and 37 to concentrically position the outer die 22 with respect to the cylindrical radial punch holder 30. At this point the bolts which pass through the plates 95 and 96 and into the tapped holes 29 and 37 on the outer faces of the assembly elements are tightened. The radial punch and die assembly 20 is also aligned by the bolts in plates 95 and 96 with the tube feeding shaft 89 and the punch forcing cone shaft 98.

The tube feeding shaft 89 is retracted and a section of tubular well casing to be slotted is'connected thereto by the coupling 92. The punch forcing cone 40 is mounted on the cone moving shaft 98 by threading its end piece 52 into a threaded end section of the shaft 98 and tightening the locking nut 54. The shaft 98 is then advanced by pulling one of the control levers 112 on pump 110 to supply fluid via the supply lines 108 to the hydraulic cylinder 106.

As the shaft 98 moves outwardly pressing the punch forcing cone 40 further into the bore of the radial punch holder 30, the pointer 102 moves along the scale 104 to the initial starting position. The end of the tubing 94 at this time is positioned within the die where the first series of slots are to be made by tube positioning shaft 89. The other of the two control levers 112 controls flow of hydraulic fluid from the pump 1 through lines 88 to the hydraulic cylinder 86 to bring about this movement. Each of the control levers on the pump 110 would have a forward, neutral, and retract position.

The slotting operation could now proceed, with the forward movement of the punch forcing cone controlled by shaft 98. The radially outward movement of the punches 42 would be controlled by movement of the pointer 102 along the scale 104. It is calibrated in tenths of an inch and this would be reflected in an equivalent radial punch travel. It has been found that the radial travel of the punch can be controlled to within thousandths of an inch. The punches travel radially outwardapproximately two-tenths of an inch for every inch of travel of shaft 98.

The shaft 98 will be moved along to provide the desired radially outward travel of the radial punches 42, which can be computed and translated to value marking on the scale 104. When that point is reached, travel of the shaft 98 is halted and the shaft travel reversed to withdraw the punches to the initial starting position, which again will be indicated by the initial scale reading. Thus the first three slots are made. In practice nine punches are usually used to punch out nine slots simultaneously. The ram 98 is then retracted to the zero or initial scale reading, and the tubing 94 is advanced further through the die assembly to a point where the second set of radial slots is to be made.

There are spaced markings 116 on the sleeve 118 which average 2% inches apart. The end of the pipe 94 is moved into telescoping engagement over sleeve 118 and the markings 116 are used to position the tubing 94 in the die assembly 20.

The well casing or tubing 94 is progressively slotted to produce three to nine rows of slotted pieces at one time, such as 14 on the well screen 10 of FIG. 1. When a row has been completed the tube 94 is turned angularly to position the punches for the start of another row, such as row of the well screen of FIG. 10, and this second set of slot rows is then produced. The process is repeated until the well casing is completely slotted to produce the desired screening.

The pipe slotting bench of FIG. 11 is of rigid construction to intake the heavy loads which are produced when well casing as thick-walled as one-quarter of an inch is slotted. Side support rails 82 are 3 inch by 10 inch channel iron frame which provides sturdy rails for the rollers of the hydraulic cylinder rolling support assembly 90. The hydraulic cylinder 86 is a 6 inch by 10 feet cylinder unit, and the shaft 89 on the hydraulic ram is 10 feet long. The overall length of the bench of FIG. 11 is 38 feet. The coupling assembly 92 is an annular collar which can either clamp or threadedly engage the end of the pipe 94 to be slotted.

' The die assembly 20 is mounted on the plate mounting assembly. It consists of the plates 95 and 96 which have an annular opening through them and an annular set of bolt holes aligned with the bolt holes 29 of the outer die. The cylindrical radial punch is bolted to the outer tubular sleeve of the cone forcing shaft assembly 98.

The pointer 102 can be mounted on shaft 98 free to travel in the groove 103 on the sleeve.

The shaft 98 assembly includes an inner power shaft which is directly screwed onto the end of the ram of the hydraulic cylinder 106, and an outer tubular sleeve 118 which slides over the shaft and through which the inner shaft is moved. It has the slot 103 which permits the travel of the pointer 102 connected to shaft 98, over scale 104. Length of scale 104 is the same as ram of cylinder 106 which is 12 inches long.

The initial position for the scale marker should be on zero and this can be set by moving the pointer 102 along the slot 103 to where it is above zero on the scale. At this point the outer surfaces of the punches 42 should be flush with the outer surface 34 of the radial punch holder 30. The amount of opening for the slotted piece is then added to the thickness of the pipe to give the length of radial travel of the punch. This length is then converted to a scale reading on scale 104. The amount of travel, as mentioned previously, can be controlled to approximately a thousandth of an inch.

The outer die assembly 20 is supported by the support plates 95 and 96. Not shown are a pair of supporting jacks which are connected to the bottom of the frame supporting the plates 95 and 96 which are used to vertically align the annular space in the radial punch and die assembly with the end of the tubing 94 to be slotted. In most instances, nine radial punches will be used with the punch and die assembly 20, using all of the nine slots 32 in the cylindrical radial punch holder 30. There are 18 longitudinal punch receiving slots 24 in the outer cylindrical die 22. Nine of these would be aligned with the nine punches supported in the radial punch support slots 32 of the cylindrical radial punch support 30.

The invention contemplates the use of different die assemblies for different nominal diameter pipes. For example, there are five varying pipe diameter sizes, each of which would require a different size punch and die assembly. For a punch and die assembly for a 6% inch pipe, the outer cylindrical die 22 has an outside diameter of 10% inches, an inside diameter of 6.685 inches, and a length of 6 inches. The 18 longitudinal slots are 0.400 inches wide and 0.750 inches deep. The alignment pin passages are one-quarter of an inch diameter and are positioned at angles. The radial punch holder has an outside diameter of 6.290 inches, an inner diameter at one end of 3.50 inches and at the other end of 2.500 inches. The slots are three-eighths of an inch by 2% inches long, extending through the punch holder wall on radial lines spaced 40 apart. The alignment pin passages are one-quarter of an inch in diameter spaced 90 apart and are aligned with the alignment pin holes of the cylindrical die.

There are nine radial punches which are 0.372 inches thick and 2% inches wide. The punches are 2 and 5/16 of an inch high at their outer edges and 2% of an inch high at the intermediate section. The distance along the cutting edge is 7and 9/16 inches. The grooves are 0.160 inches wide and one-sixteenth of an inch deep, and are located one-eighth of an inch from the bottom edge. The dies are three-thousandths of an inch less in thickness than the width of the slots in the radial die holder.

The punch forcing cone has a diameter of two inches on the small end and a diameter of three inches on its large end. The nine T-shaped holding grooves are onequarter of an inch wide and 0.325 inches deep. They are 12 inches long, and at their bottom portion at the top of the T are three-eights of an inch wide and oneeighth of an inch thick.

Well casing tube lengths of 5 to feet are usually the length of pipe slotted. The slot openings can be varied as desired, and ordinarily a range of from tenthousandths to two-tenths of an inch is selected, depending upon the type of sand or gravel encountered.

The punch and die assembly can be used to slot tubing having a wall thickness of from one-tenth to onequarter of an inch.

ADVANTAGES The above described invention makes it possible to provide a well screening which uses regular well casing, and does not affect its wall thickness.

The manufactured well pipe using the radial punch and die above-described provides a perfectly round, undistorted tube which is straight and has no distortions, such as are encountered with pre-stamped and rolled sheet metal screens. Well casing slotted according to this invention are true to within fifteenthousandths of an inch.

The invention provides a simple and readily set-up machine unit, relatively inexpensive to manufacture and maintain, and yet which provides a wide range of slot opening sizes for screening out a wide range of different size and types of material.

The invention offers versatility in selecting screens for use with different material, since the distance between slot openings, and the size of the slot openings can readily be varied.

While the invention has been described, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations of the invention following in general the principles of the invention andincluding such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains, and as may be applied to the essential features hereinbefore set forth and as fall within the scope of the invention or the limits of the appended claims.

What I claim is:

1. A tube slotting machine comprising:

a. an elongated support bench,

b. a radial punch receiving die having a cylindrical bore which is mounted at the mid-section of the support bench and axially aligned with the longitudinal direction of the bench,

c. the punch receiving die having longitudinally extending punch receiving grooves extending along the peripheral surface adjacent the bore,

tube support and moving means at one end of the bench for supporting and moving a piece of tubing through the bore of the punch receiving die,

e. radial punch means disposed within the bore of thepunch receiving die and having a plurality of radial punches radially aligned with the punch receiving grooves for moving punches outwardly against the inner wall of the tubing and into the punch receiving grooves,

f. power means disposed at the other end of the bench and connected to the radial punch means for providing power to the punch means for movingthe radial punches.

2. The tube slotting machine of claim 1, wherein:

a. the radial punch includes a cylindrical surfaced support member concentrically positioned within and spaced from the bore surface of the outer die which has radial punch support slots extending radially outward within which the radial punches are supported.

3. The tube slotting machine a punch forcing member wherein:

a. the radial punch means includes a punch forcing member having a tapered surface which engages and moves the radial punches outwardly.

4. The tube slotting machine of claim 3, including:

a. a cylindrical surfaced radial punch support member having radial punch support slots and a central bore into which the punch forcing member is received.

5. The tube slotting machine of claim 1, wherein:

a. the power means includes a hydraulic ram having an elongated shaft which is operably connected to the radial punch means.

6. The tube slotting machine of claim 5, wherein:

a. the elongated shaft has scale and pointer means associated therewith for determining the amount of radial outward travel of the punches.

7. A tube slotting machine, comprising:

a. an elongated support bench,

b. a radial punch and die assembly mounted at the mid-section of the support bench and positioned to receive tubing fed longitudinally along the support bench,

c. power and tube support means at one end of the bench for supporting and moving the length of the tubing longitudinally along said bench and through the die assembly,

. one of the elements of the power and die assembly being an outer die having a cylindrical longitudinal bore therethrough with longitudinal punch receiving grooves on the inner surface adjacent the bore,

e. another of the elements of the punch and die assembly being a cylindrical radial punch holder concentrically positioned within the bore of the outer die and spaced therefrom to provide an annular space for accommodating a section of the tubing,

f. the punch holder having a bore extending longitudinally therethrough, and a plurality of radially extending slots extending through the punch holder and aligned with the longitudinal groove of the outer die,

g. a radial punch disposed within each radial slot and of slightly less cross-sectional size than the slots, with the height of the punches being greater than the radial dimension from the inner bore of the punch holder to the peripheral surface adjacent the bore of the outer die,

h. power and support means disposed at the other end of the bench for supporting and moving a punch forcing member into the bore of the radial punch holder,

i. the punch forcing member having a tapered surface which engages and forces the radial punches radially outward.

8. The tube slotting machine of claim 7, wherein:

a. the punch forcing member has connecting means on its tapered surface to engage the radial punches for moving the punches both radially, outwardly and inwardly.

9. The tube slotting machine of claim 7, wherein:

a. the innermost radially disposed section of the punches has a longitudinally extending slot,

b. the tapered surface of the punch forcing member has a longitudinally extending shoulder which engages the groove of the corresponding radial punch.

10. The tube slotting machine of claim 7, wherein:

a. the punch forcing member has a conical surface having a plurality of longitudinally extending T- shaped grooves aligned with the radial slots of the radial punch holder,

b. the radial punches have their lower section configured and dimensioned to fit within the corresponding T-shaped groove on the punch forcing member.

1 l. The tube slotting machine of claim 7, wherein:

a. the radial punch and die assembly includes means for accurate alignment of the longitudinal grooves of the outer die with the radial punch support slots of the radial punch holder.

12. The tube slotting machine of claim 7, wherein:

a. the radial punch and die assembly includes internal lubricating means for providing relative ease of movement between adjacent surfaces of the assembly. 

1. A tube slotting machine comprising: a. an elongated support bench, b. a radial punch receiving die having a cylindrical bore which is mounted at the mid-section of the support bench and axially aligned with the longitudinal direction of the bench, c. the punch receiving die having longitudinally extending punch receiving grooves extending along the peripheral surface adjacent the bore, d. tube support and moving means at one end of the bench for supporting and moving a piece of tubing through the bore of the punch receiving die, e. radial punch means disposed within the bore of the punch receiving die and having a plurality of radial punches radially aligned with the punch receiving grooves for moving punches outwardly against the inner wall of the tubing and into the punch receiving grooves, f. power means disposed at the other end of the bench and connected to the radial punch means for providing power to the punch means for moving the radial punches.
 2. The tube slotting machine of claim 1, wherein: a. the radial punch includes a cylindrical surfaced support member concentrically positioned within and spaced from the bore surface of the outer die which has radial punch support slots extending radially outward within which the radial punches are supported.
 3. The tube slotting machine a punch forcing member wherein: a. the radial punch means includes a punch forcing member having a tapered surface which engages and moves the radial punches outwardly.
 4. The tube slotting machine of claim 3, including: a. a cylindrical surfaced radial punch support member having radial punch support slots and a central bore into which the punch forcing member is received.
 5. The tube slotting machine of claim 1, wherein: a. the power means includes a hydraulic ram having an elongated shaft which is operably connected to the radial punch means.
 6. The tube slotting machine of claim 5, wherein: a. the elongated shaft has scale and pointer means associated therewith for determining the amount of radial outward travel of the punches.
 7. A tube slotting machine, comprising: a. an elongated support bench, b. a radial punch and die assembly mounted at the mid-section of the support bench and positioned to receive tubing fed longitudinally along the support bench, c. power and tube support means at one end of the bench for supporting and moving the length of the tubing longitudinally along said bench and through the die assembly, d. one of the elements of the power and die assembly being an outer die having a cylindrical longitudinal bore therethrough with longitudinal punch receiving grooves on the inner surface adjacent the bore, e. another of the elements of the punch and die assembly being a cylindrical radial punch holder concentrically positioned within the bore of the outer die and spaced therefrom to provide an annular space for accommodating a section of the tubing, f. the punch holder having a bore extending longitudinally therethrough, and a plurality of radially extending slots extending through the punch holder and aligned with the longitudinal groove of the outer die, g. a radial punch disposed within each radial slot and of slightly less cross-sectional size than the slots, with the height of the punches being greater than the radial dimension from the inner bore of the punch holder to the peripheral surface adjacent the bore of the outer die, h. power and support means disposed at the other end of the bench for supporting and moving a punch forcing member into the bore of the radial punch holder, i. the punch forcing member having a tapered surface which engages and forces the radial punches radially outward.
 8. The tube slotting machine of claim 7, wherein: a. the puncH forcing member has connecting means on its tapered surface to engage the radial punches for moving the punches both radially, outwardly and inwardly.
 9. The tube slotting machine of claim 7, wherein: a. the innermost radially disposed section of the punches has a longitudinally extending slot, b. the tapered surface of the punch forcing member has a longitudinally extending shoulder which engages the groove of the corresponding radial punch.
 10. The tube slotting machine of claim 7, wherein: a. the punch forcing member has a conical surface having a plurality of longitudinally extending T-shaped grooves aligned with the radial slots of the radial punch holder, b. the radial punches have their lower section configured and dimensioned to fit within the corresponding T-shaped groove on the punch forcing member.
 11. The tube slotting machine of claim 7, wherein: a. the radial punch and die assembly includes means for accurate alignment of the longitudinal grooves of the outer die with the radial punch support slots of the radial punch holder.
 12. The tube slotting machine of claim 7, wherein: a. the radial punch and die assembly includes internal lubricating means for providing relative ease of movement between adjacent surfaces of the assembly. 